Found somewhere in the dictionary between omphalos and onocrotal, and bearing no relation to nothus is:
*** ONCETHMUS ***
Please send me your fabulous, fanciful, fictitious, fairy-tale, fabricated, false, fantastical, forged, fabled, far fetched, fraudulent, flimflam, feigned, fanatical, and figmental fake definitions for ONCETHMUS by email to widdis (at) dixonary (dot) net.
I’ll reset the deadline to 36 hours from now: please submit your definitions by 7 am PDT at the Griffith Observatory in Los Angeles on Monday, August 10 which is 10 am EDT at the US Naval Observatory in Washington DC, 14:00 UTC on the International Space Station, 3 pm BST at the Greenwich Meridian and elsewhere in the UK, 4 pm CEST at la Méridienne de France and in most of Europe, and 2 am NZST on Tuesday at the Amundsen–Scott South Pole Station.